1. Field of the Invention
The present invention relates to valves for modulating fluid flow, and more particularly to trim valves for modulating fuel flow in gas turbine engines.
2. Description of Related Art
A variety of devices and methods are known in the art for regulating fluid flow. For example, there have been many devices for regulating fuel flow in fuel injectors and nozzles during operation of gas turbine engines. Of such devices, many are directed to manifolds, valves, and check valves for regulating fuel flow through injectors and nozzles in an effort to maintain even flow distribution among multiple fuel injectors.
During operation of typical gas-turbine engines, fuel is supplied at a set mass flow rate to a manifold by a fuel pump, which creates the pressure needed to simultaneously deliver the required mass flow rate to a plurality of fuel injectors. The fuel injectors are typically arranged in a circumferential pattern around the combustor of the engine. Due to manufacturing tolerances and material variations in the fuel injectors, the fuel flow from individual injectors can vary significantly from injector to injector even if the manifold and other engine components are functioning properly. In the past, this problem has been addressed by tightening manufacturing tolerances for engine components and particularly for the injectors. There are practical limitations to this approach. Additionally, regardless of how tight the manufacturing tolerances are, uneven flow can result from variations in wear from injector to injector over the lifetime of the injectors.
The effect of variations from injector to injector due to uneven wear, manufacturing tolerances, and other factors can cause significant maldistribution of fuel flow from one injector to the next. This uneven distribution of fuel can create difficulties in operating and maintaining gas turbine engines, such as poor fuel performance, elevated emission of pollutants, and combustor stress due to temperature gradients, i.e. hot spots and cold spots, around the combustor.
The conventional methods and systems described above have generally been considered satisfactory for their intended purposes. However, there still remains a continued need in the art for devices and methods that allow for improved flow distribution among multiple fuel injectors. There also remains a need in the art for such methods and devices that are easy to make and use. The present invention provides a solution to these problems.